Actuator for generating tool head

ABSTRACT

A motion conversion apparatus is disclosed having particular utility as a tool carrier actuator in a rotating taper thread generating tool head, wherein a plurality of tool carriers are moved axially of the workpiece and simultaneously transversly of the axis to form a tapered thread at the end of the workpiece. A portion of the actuating apparatus is mounted coaxially with a housing for the tool head and includes an inner and an outer actuating bar coupled together by helical keys and mating keyways such that relative axial motion between the inner and outer bars produces rotating movement of the outer bar. Rotation of the outer actuating bar is transferred to an actuating drum which has an outer surface having at least one helical keyway formed therein. In one embodiment, the actuating drum is a separate component rotating with the outer actuating bar via key-keyway pairs. A driven sleeve surrounds a portion of the actuating drum and is keyed to the helical keyway in a manner such that a given rotation of the drum produces a proportional axial linear movement by the sleeve.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is generally related to motion conversion apparatus. Moreparticularly, the invention is concerned with tool slide actuation in agenerating tool head wherein at least one tool point is capable ofsimultaneous axial and transverse motion relative to a work surface onwhich tapered threadforms are to be generated. 2.

Description of the Prior Art

While the invention is useful in a variety of mechanical systems, it isdescribed herein for use with a taper thread generating head coupled tothe spindle assembly of a pipe threading machine tool system. Suchthreading systems are known and are set up to perform the generaloverall task of generating an external tapered thread at the end of pipesections appropriately chucked in substantial axial alignment with thegenerating head. As the housing of the tool head is advanced axially ofthe pipe section, or other workpiece, thread cutting elements are movedaxially as well as radially, or transversely, of the toolhead axis tothereby generate a thread form which gradually tapers outwardly suchthat the maximum depth of cut occurs at the end of the pipe or workpiecefirst engaged by such cutting elements. At the end of the cuttingstroke, or threading pass, the cutting elements must be further movedtransversely of the tool head housing axis to provide clearance betweenthe pipe or workpiece and the cutting elements as the tool head isbacked away to a restart position for the next pipe or workpiece to bethreaded.

The motion conversion apparatus employed in these prior art threadgenerating heads typically comprises complicated camming elements, oftenrequiring a separate camming mechanism for converting axial totransverse motion for each of a plurality of cutting tool holdersassociated with the generating head. Providing separate mechanisms foreach holder may lead to component matching problems preventinguniformity of movement of each cutting element with respect to theworkpiece. Additionally, the linear or arcuate camways and associatedcam followers of the prior art motion conversion apparatus are oftenunsuited for the higher speeds and feeds which may be typically employedwith carbide cutting elements.

The most pertinent prior art known to applicant is set forth in thedisclosures of the following United States Letters Patent:

U.S. Pat. No. 2,054,028, Benninghoff, Sept. 8, 1936

U.S. Pat. No. 3,812,548, Theuerkaue, May 28, 1974

U.S. Pat. No. 3,129,445, Jennings, April 21, 1964

U.S. Pat. No. 3,254,548, Gersch, June 7, 1966

U.S. Pat. No. 3,286,556, Reynolds et al., Nov. 22, 1966

U.S. Pat. No. 3,443,458, Ohrnberger et al., May 13, 1969

U.S. Pat. No. 4,004,332, Wawrzniak, Jan. 25, 1977

U.S. Pat. No. 4,040,315, Bellingham, Aug. 9, 1977

U.S. Pat. No. 4,066,380, Beck et al., Jan. 3, 1978

It will therefore be seen that there is a need in the pertinent artfield for a motion conversion mechanism capable of smoothly convertingmechanical motion of cutting elements of generating heads capable of usewith a variety of machine tool spindle assemblies at relatively higherfeeds and speeds than in the past, and capable of being relativelyeasily manufactured and assembled. Further, a review of the prior artdemonstrates a need for such apparatus that is capable of being at leastmanually adjustable as to its produced results without complicateddisassembly of many of the components of the apparatus being required.

SUMMARY OF THE INVENTION

With an object of overcoming deficiencies in the prior art, actuatingapparatus is disclosed for use, for example, with a generating headcoupled to the spindle assembly of a machine tool. A three or four piececoaxially mounted novel assembly of components converts movement of aninput member to a proportional movement of an output member. The inputmember is coupled to one of an inner actuating bar and an outeractuating bar, the inner and outer bars coupled together via matinghelical actuating surfaces, such that relative axial linear motionbetween the inner and outer bars produced by movement of the inputmember produces rotational movement about its longitudinal axis by theouter actuating bar. The outer actuating bar has means at an outersurface thereof for driving a coupling element or key with an axiallylinear motion proportional to the rotation of the outer bar. The outputmember is provided this proportional linear motion by mounting thecoupling element key in an inner surface of the output member whichcoaxially surrounds a portion of the means at the outer surface of theouter actuating bar.

In a preferred use of the invention, the means at the outer surface atthe outer actuating bar comprises a separate actuating drum keyed forrotation with the outer actuating bar. The actuating drum has at leastone helical slot or keyway in which at least one key protruding from aninner surface of the surrounding output member is slidingly engaged.Alternate keyways in the actuating drum may be provided such thatdifferent axially linear movements proportional to drum rotation may beappropriately preselected by proper positioning of the key coupling theoutput member to the drum. By providing a separate actuating drum, theouter actuating bar may move axially as well as rotationally, while theactuating drum may be held against axial movement.

In the preferred taper thread generating head disclosed herein, theabove summarized apparatus comprises a portion of an actuator for aplurality of cutter carrying tool blocks which simultaneously moveaxially and radially of a workpiece being taper turned and threaded in asingle pass along the workpiece. The output member has a keywayextending circumferentially about an outer surface of the output memberand is keyed therefrom to a plurality of crank actuator bars extendingsubstantially parallel to the axis of the head and workpiece. Eachactuator bar is, in turn, coupled to a corresponding tool slide via abell crank mechanism in a manner such that axial motion of the actuatorbars imparted thereto by the output member causes each tool slide tomove a proportional distance transverse to the axis of the head andworkpiece. In a more specific preferred form, an even number of toolslides are provided, with every other slide driving a tool blockmounting a circular taper turning cutting insert axially leading amulti-tooth thread chasing cutting insert. The remainder of the toolslides drive a tool block mounting only a circular taper turning insert.

BRIEF DESCRIPTION OF THE DRAWING

The objects and features of the invention will become apparent from areading of a detailed description of a preferred embodiment, taken inconjunction with the accompanying drawing in which:

FIG. 1 is a side elevation of a machine tool system with a combinedtaper turning, thread generating head utilizing the present invention;

FIG. 2 is a partial sectional view of the generating head depicted aspart of FIG. 1, taken normal to the longitudinal axis of the headhousing;

FIG. 3 is a partial end view along the axis of the generating head ofFIG. 2 from the tool mounting end thereof with certain elements shown inFIG. 2 deleted for clarity; and

FIG. 4 is an exploded perspective view of the coaxially mounted portionof the actuator apparatus shown operatively mounted within thegenerating head of FIGS. 2 and 3.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

For clarifying consistency, the same reference numerals are applied tothe same components throughout the drawing figures.

With reference to FIG. 1, a machine tool system is depicted forutilizing a tapered thread generating head 100 incorporating the novelapparatus of the invention. To a base 111 of the system is mounted aspindle carriage and drive component 105, which includes appropriatehorizontal ways (not specifically shown) for reciprocating movement ofspindle assembly 104 and the head 100 coupled thereto. Component 105additionally includes a suitable drive motor (not specifically shown)for spindle assembly 104. Also mounted to base 111 is a suitablechucking mechanism 103 for clamping a workpiece, such as a circular pipeW, in substantially axial alignment with the longitudinal axis ofhousing 200 of head 100.

At an end facing workpiece W, head 100 has mounted thereto a plurality,e.g. six, of tool slides 102 each carrying a tool holder 101 inradially, i.e. transversely of the axis of head 100, sliding fashion.Every other tool holder 101 carries a circular taper turning cuttinginsert 114 followed by a multi-toothed thread chaser cutting inser 115in substantial axial alignment with its corresponding preceeding insert114. The remainder of the tool holders 101 carry only a taper turningcircular inser 114. For illustrative purposes, one of each type toolholder is depicted in FIG. 1, the dual insert type shown above workpieceW, and the single insert type shown therebelow.

Axially aligned with workpiece W is a stop collar 113 coupled to theactuating apparatus inside housing 200 of head 100, such apparatus to bedescribed in further detail in a later portion of this description.

A pilot portion 204 of head 100 extends into hollow spindle assembly104. Also extending into the interior chamber of spindle 104 is one endof the coaxially mounted portion 40 of the acutating apparatus of theinvention. Coupled to portion 40 is a drawbar 112, in turn coupled to apiston rod of piston 107 which reciprocates within hydraulic cylinderhousing 106 under the control of hydraulic control circuit 110 coupledto cylinder 106 via hydraulic conduits 108 and 109.

In general operation, spindle carriage and driver 105 advances spindleassembly 104 and head 100 axially toward workpiece W whilesimultaneously rotating spindle 104 and head 100 about a longitudinalaxis in substantial alignment with that of workpiece W. Upon engagementof the end of workpiece W by stop collar 113, carriage 105 continues tomove the housing 200 of head 100 axially along workpiece W and collar113 imparts the necessary input motion to actuating apparatus 40 toinitiate a simultaneous radial, or transverse, movement to tool slides102 as the tool carriers 101 move axially along the outer surface ofworkpiece W. Hence a gradually decreasing taper surface is rough turnedby inserts 114 and a thread form is generated thereon by followingchaser inserts 115. At the conclusion of the combined taperturning-thread generating pass, carriage 105 halts axial movement ofhousing 200. At this point, control 110 causes hydraulic cylinder 106 toforce piston 107 and connected drawbar 112 a predetermined distancetowards apparatus 40 thereby effecting further transverse or radialmovement of slides 102 in an amount sufficient to provide suitableclearance between all cutting inserts 114, 115 and the exterior surfaceof workpiece W as the head 100 is axially retracted to a startingposition in preparation for initiating a subsequent machining pass alonga new workpiece. The manner in which motion of drawbar 112 againstapparatus 40 produces transverse motion of slides 102 will be describedin a later portion of this description.

While the invention is illustrated in conjunction with a system asabovedescribed, it will be apparent to those skilled in the art thatapparatus designed in accordance with the principles of the inventioncould also be adapted for use with a stationary generating head engaginga rotating workpiece. Likewise, such apparatus could be adapted fortaper threading of an interior surface of a workpiece. Additionally itshould also be appreciated tht the invention is easily adapted for usewith a variety of actuating mechanisms for drawbar 112, be theyhydraulic of electrical in nature.

With reference now to FIGS. 2, 3 and 4, the structure and mountingrelationship to the head housing of the actuator for the tool slides 102will be described in more detail.

Housing 200 of head 100 is provided with a frontal portion of enlargeddiameter containing a plurality (e.g. 6) of tool slides 102 eachslidingly carrying a tool holder 101 on a radially extending slideway201 and coupled to each tool holder 101 via a thrust key 214.

Coaxially mounted to head 100 at the tool holder end thereof, is stopcollar 113 attached to a bearing housing 202 at groove 211 via suitablyshaped cone point screws (not specifically shown).

At an opposite end of heat 100 is provided a spindle pilot portion 204with an axial rearward extension adapted to engage the interior hollowportion of spindle assembly 104. A flanged section of pilot portion 204is coupled to the spindle shaft 104 via a plurality of bolts 213, one ofwhich is shown in the view of FIG. 2.

Slidingly mounted coaxial to and within an internal cavity of spindlepilot portion 204 is a tail section 205 having a threaded extension 205Aprotruding from a bore in rear wall 208 of pilot portion 204. Threadedto extension 205A is a pair of stop nuts 207, 209 separated by washer210. Tail section 205 is keyed for rotation with spindle pilot portion204 via key 229, while spindle pilot portion 204 causes housing 200 torotate with portion 204 via a plurality of dowel pins 212, one of whichis shown in the view of FIG. 2.

The coaxially mounted portion 40 of the tool carrier actuatingapparatus, comprises an inner actuating bar 1 having a flanged endportion 10 coupled to tail section extension 205A. Mounted in an inneraxial bore 11 of bar 1 are springs 240 and 241 and spring pilot 242.Spring 241 bears against flanged portion 10 of bar 1, while spring 242bears against an end cap portion of bearing retainer 227.

Slidingly mounted around inner actuating bar 1 is an outer actuating bar2. As best seen from FIG. 3 and FIG. 4, outer bar 2 has four helicalkeyways 24, 25, 26, 27 shaped for mating engagement respectively withhelical keys 14,15,12 and 13 protruding from inner actuating bar 1. Aforward end of bar 2 abuts against bearing housing 202 such that axialmovement of stop collar 113 is transmitted via slidingly mounted housing202 to outer actuating bar 2. Surrounding a portion of outer actuatingbar 2 is an actuating drum 3, which is mounted for rotation with outerbar 2 via a pair of keys 246, one of which is shown in the view of FIG.2. Keys 246 are slidable in keyways 21 and 22 (FIG. 4) of bar 2 and arecaptively mounted in cavities 303 and 304 formed in an inner surface ofactuating drum 3 (FIG. 3). Actuating drum 3 is mounted for substantiallyfrictionless rotation within housing 200 via bearings 243, which ride onextensions 33 of drum 3.

The outer surface of drum 3 is provided with 2 pairs of helical slots orkeyways 31 and 32 (only one slot of each pair being visible in FIGS. 2and 4). The helix angle for pair 31 is different from that for pair 32for purposes to be explained later.

Keyed to one of the two pairs of helical keyways 31, 32 is an outerdriven sleeve, or output member, 4 via a pair of identical keys 301 and302 (FIG. 3) housed in cavities 42A and 42B of sleeve 4 whenever usedwith keyway pair 31, or housed in cavities 43A and 43B whenever usedwith keyway pair 32. Sleeve 4 is keyed for rotation with housing 200 viakey 228 slidingly engaging keyway 41 of sleeve 4 (FIG. 4).

Three bearing pre-load bars 225 (one of which is shown in the view ofFIG. 2) extend from tail section 205 through bores 44A, 44B and 44C ofsleeve 4 (FIG. 4) into bearing retainer 227. Each preload bar 225 isbiased by a spring 226.

Extending circumferentially about an outer cylindrical surface of sleeve4 is an output keyway 224 shaped for receipt of a plurality (e.g. 6) ofkeys 222 protruding from associated crank actuator bars 221. Keys 222are held substantially immobile with respect to bars 221 viakey-receiving cavities 223. As seen from FIG. 2, crank actuator bars 221are slidingly mounted in housing 200 substantially parallel to the axisthereof. Each crank actuator bar is keyed for rotation with housing 200via keys 230. At an end opposite to that keyed to the sleeve 4, eachcrank actuator bar 221 is coupled via a first axle pin 218 to a firstportion 216 of actuating arm 215. Actuating arm 215 is pivotally mountedto housing 200 via main axle 220. Each tool slide 102 is coupled to asecond portion 217 of actuating arm 215 via a second axle pin 219.Actuating arm 215 with its associated main axle and slotted arm portionsis seen to comprise a conventional bell crank mechanism.

Workpieces of varying diameters can be accommodated by the generatinghead 100, due to the adjustable mounting arrangement of tool slides 102to housing 200, best shown in FIG. 3, an end view of the generating headin which the tool holders 101 are not shown for a clearer presentationof the apparatus mounted axially rearwardly of the tool holders 101. Asseen from FIG. 3, each tool slide 102 is mounted to tool head housing200 by means of screws 321 in a manner in which the initial setting ofeach slide 102 is made radially adjustable by provision of elongatescrew receiving slots 320 in housing 200.

Also seen in FIG. 3 are generally pie segment shaped cover plates 311mounted between each pair of tool slides 102 at the forward end of toolhead housing 200. Appropriately positioned on each cover plate 311 is afitting 310 arranged for directing lubricating fluid toward each toolslide.

With the preferred structural arrangement set forth above, the operationof the actuator mechanism may be summarized as follows.

Upon axial movement of generating head 100 towards the workpiece W byspindle carriage 105, stop collar 113 comes into contact with the end ofworkpiece W. Continued axial motion of housing 200 therefore results inthe outer actuating bar 2, which, via bearing housing 202 and bearingretainer 227, is responsive to pressure on collar 113, to move axiallyrearwardly with respect to inner actuator bar 1. Such rearward axialmovement of bar 2 results in rotation of bar 2 due to the helicalinteraction surfaces provided by keys 12,13,14,15 respectively engagingkeyways 26,27,24,25 of outer actuator bar 2.

In response to rotating movement of outer actuator bar 2, actuating drum3 likewise rotates due to keys 246 protruding from cavities 303 and 304of drum 3 and slidingly engaging keyways 21 and 22 of outer bar 2. Whileouter bar 2 is mounted for sliding axial motion with respect to housing200, drum 3 is not. Hence relative axial movement of bar 2, combinedwith rotational movement of bar 2, is translated into solely rotationalmovement of drum 3 with respect to housing 200.

Keys 301 and 302 (FIG. 3) positioned in one of the two pairs of helicalslots 31 or 32 of drum 3, impart linear axial movement to sleeve 4 uponrotation of drum 3. The linear axial movement of sleeve 4 is, in turn,transferred to each of the plurality of crank actuator bars 221 via keys222, keyway 224, in sleeve 4 and key receiving cavities 223 in eachcrank actuator bar 221. In the preferred embodiment, at least two pairsof keyways, each with a different helix angle, are provided so that theuser may manually select one of two available tapers by appropriatelyinserting keys 301 and 302 into a preselected keyway pair.

Hence to this point of the description, housing 200 has been moved in adirection shown by arrow 244 (FIG. 2) with respect to workpiece W,thereby likewise axially moving inserts 114 and 115 of each tool carrier101 axially along workpiece W. Additionally, due to the cooperatingmovement of the various elements of the coaxial portion 40 of theactuating mechanism of the invention, sleeve 4 has been simultaneouslyaxially moved a distance determined by the combination of the relativeaxial movement between actuating bars 1 and 2, and the rotationalmovement of actuating drum 3, along with the pre-chosen pair of helicalkeyways 31 or 32 in the actuating drum 3.

The axial movement of sleeve 4 is converted into radial or transverse,movement of each tool slide 102 via the bell crank mechanism associatedwith each crank actuator bar 221 keyed to sleeve 4. Hence inserts 114,115 of alternate tool carriers 101, and insert 114 of the remaining toolcarriers are simultaneously moved axially and radially, or transverse tothe axis, of the workpiece W to generate a desired tapered thread. Tosummarize, relative axial linear motion of bars 1 and 2 is converted tosolely rotational movement of drum 3, which, in turn, is converted viakeyways 31 or 32 to linear axial motion of sleeve 4. Axial motion ofsleeve 4 is, in turn, converted to motion substantially transverse tothe axis of head 100 by bell crank mechanisms each comprised of elements215, 216, 217, 218, and 219 actuated by bars 221, in turn driving eachof the plurality of tool slides 102 and their associated tool carriers101 via thrust keys 214.

Hence the coaxially mounted apparatus 40, in combination with the motionconverters comprising actuator bars 221 and associated bell crankmechanisms 215, 216, 217, 218, 219, produces transverse motion of toolslides 102 proportional to axial motion of the housing 200 relative tothe workpiece by an amount determined by (a) the helix angle of thekey-keyway surfaces of actuator bars 1 and 2, (b) the helix angle of thekeyways 31 or 32 on the outer surface of drum 3, and (c) the mechanicaladvantage provided by the bell crank mechanism. By providing more thanone pair of helical keyways on the outer surface of actuating drum 3,the proportional transverse motion of tool slides 102 can be manuallypreselected by placing keys 301, 302 in keyways 31 or keyways 32, eachhaving a different helix angle.

At the end of the combined taper turning and threading operation alongthe outer surface of workpiece W, movement of housing 200 in thedirection indicated by arrow 244 (FIG. 2) is stopped by spindle carriage105. Prior to retraction of housing 200 away from workpiece W in thedirection of arrow 245 (FIG. 2), each insert 114, or inserts 114 and 115as the case may be, of tool carriers 101 must be moved away from theouter surface of workpiece W by an amount sufficient to provideclearance between all cutting inserts and workpiece W as housing 200 isaxially withdrawn from workpiece W. Such clearance is provided asfollows.

At the completion of the combined taper turning and threading stroke ofhousing 200 in the direction of arrow 244, housing 200 is heldstationary with respect to workpiece W by spindle carriage 105 whilecontrol circuit 110 causes hydraulic cylinder 106 to force piston 107toward head 100, as viewed in FIG. 1. Such movement of piston 107, inturn, via draw bar 112, forces inner actuating bar 1 to axially movetail section 205 in the direction of arrow 244, via flanged portion 10.Such axial movement of tail section 205 is, in turn, transmitted tosleeve 4, which, via bars 221 and crank actuating arms 215, furthermoves tool slides 102 radially outwardly of the workpiece an amountsufficient to provide the desired clearance, while housing 200 is beingheld stationary with respect to workpiece W. The amount of movement oftail section 205 produced by corresponding movment of drawbar 112 isgoverned by rear wall 203 of pilot portion 204 in conjunction with asurface on stop nut 209 facing wall 203. The position of stop nut 209relative wall 203 determines distance 208 (FIG. 2), the length of theretract stroke of drawbar 112.

After such sufficient radial, or transverse, clearance has been soprovided, housing 200 can be retracted in the direction of arrow 245(FIG. 2) by spindle carriage 105. Either simultaneously or subsequent tothis axial retract movement of housing 200, control 110 causes hydrauliccylinder 106 to force piston 107 rearwardly of head 100, which, in turn,causes inner bar 1 and tail section 205 to move axially rearwardly untiltail section 205 comes to rest against a plurality of stop members 206,comprised of set screws housed in pilot portion 204, one screw 206 beingshown in the view of FIG. 2. At this time, the generating head cuttingelements have been repositioned, or initialized, in preparation fortaper threading of a new workpiece.

The invention has been described above in an illustrative embodiment forthe sake of example only. Alternative approaches using the principles ofthe invention will be apparent to those skilled in the art. For example,one alternative approach would be to couple the inner actuating bar 1 tothe stop collar 113 to produce relative movement between bars 1 and 2upon contact of the workpiece by stop collar 113. In such anarrangement, where outer actuating bar 2 could be constrained againstaxial movement relative housing 200, actuating drum 3 could be combinedwith bar 2 as an integral unit resulting in only 3 detachably coupledelements or members comprising apparatus 40.

As a further alternative approach, apparatus 40 (FIG. 4) could be usedto convert rotary motion of an input member such as housing 200, toproportional rotary motion by the sleeve or output member 4. Thus twotypes of motion, rotary or linear, may be used as inputs to theapparatus of the instant invention.

Further alternatives will be suggested to those skilled in the art bythe teachings set forth herein. The invention is to be limited solely bythe scope and spirit of the appended claims.

What is claimed is:
 1. Apparatus for moving an output member in responseto movement of an input member comprising:first and second members;means coupling at least one of the first and second members to the inputmember for providing relative linear movement between the first andsecond members in response to movement by the input member; means forimparting rotary movement to the second member in response to therelative linear movement, the means for imparting rotary movementcomprising at least one helical key protruding from one of the first andsecond members and at least one helical slot in the other of the firstand second members matingly engaging at least a portion of the at leastone helical key; and means for imparting linear movement to the outputmember in response to a rotary movement by the second member. 2.Apparatus as set forth in claim 1 wherein the means for imparting linearmotion to the output member comprises:a generally cylindrical key; atleast one helical keyway formed in one of the second and output membersand at least one cavity formed in the other of the second and outputmembers, the helical keyway slidingly receiving one end of the key, andthe cavity matingly receiving another end of the key in substantiallynon-moving fashion.
 3. Apparatus as set forth in claim 1 wherein thesecond member comprises first and second portions movable relative toeach other, the at least one helical key protruding from one of thefirst and the first portion of the second members and the at least onehelical slot positioned in the other of the first and the first portionof the second members.
 4. Apparatus as set forth in claim 3 furthercomprising means for imparting only rotary motion to the second portionof the second member in response to combined linear and rotary motion ofthe first portion of the second member, the means for imparting linearmovement to the output member including a generally cylindrical key, atleast one helical keyway formed in one of the second portion of thesecond and the output members, at least one cavity formed in the otherof the second portion of the second and the output members, the helicalkeyway slidingly receiving one end of the generally cylindrical key, andthe cavity matingly receiving another end of the cylindrical key insubstantially non-moving fashion.
 5. In a toolhead for moving at leastone tool carrier relative to a workpiece in directions both parallel andtransverse to an axis of the head in response to axial movement of ahead housing relative to the workpiece, tool carrier actuating meanscomprising:first, second and output members; means coupled to one of thefirst and second members and positioned for abutting engagement with theworkpiece operative to produce relative axial movement between the firstand second members upon relative axial movement between the housing andthe workpiece; means for imparting rotary movement to the second memberin response to the relative axial movement between the first and secondmembers comprising at least one helical key protruding from one of thefirst and second members and at least one helical slot in the other ofthe first and second members matingly engaging at least a portion of theat least one helical key; means for imparting linear axial movement tothe output member in response to the rotary movement of the secondmember; and motion conversion means coupled between the output memberand the at least one tool carrier operative to generate movement of thetool carrier in a direction transverse to the head axis by an amountproportional to the axial movement of the output member.
 6. Theactuating means of claim 5 wherein the means for imparting linear axialmovement to the output member comprises at least one generallycylindrical key, at least one helical keyway formed in one of the secondand output members, at least one cavity formed in the other of thesecond and output members, the helical keyway slidingly receiving oneend of the key, and the cavity matingly receiving another end of the keyin substantially non-moving fashion.
 7. The actuating means of claim 5wherein the second member comprises first and second portions movablerelative to each other, the at least one helical key protruding from thefirst member, and the at least one helical slot formed in the firstportion of the second member.
 8. The actuating means of claim 7 furthercomprising means for imparting only rotary motion to the second portionof the second member in response to combined linear axial and rotarymotion of the first portion of the second member, the means forimparting linear axial movement to the output member including at leastone generally cylindrical key, at least one helical keyway formed in thesecond portion of the second member, at least one cavity formed in theoutput member, the helical keyway slidingly receiving one end of thegenerally cylindrical key, and the cavity matingly receiving another endof the cylindrical key in substantially non-moving fashion.
 9. Theactuating means of claim 5 wherein the output member includes an outersurface containing an output keyway, and wherein the motion conversionmeans further comprises:a connecting link having a link keyway formedtherein; an output key engaging the output and link keyways forproducing linear axial motion of the connecting link in repsonse tolinear axial motion of the output member; slide means carrying the atleast one tool carrier and coupled to the housing for relative motiontransverse to the axis thereof; and pivotally mounted crank means havinga first portion coupled to the connecting link and a second portioncoupled to the slide means, operative to pivot in response to axiallinear motion of the connecting link to cause movement of the slidemeans transverse to the axis of the housing.
 10. The actuating means ofclaim 5 further comprising retract means coupled to one of the first andsecond members for imparting additional relative axial movement to theoutput member while the housing is stationary relative the workpiece.11. In a thread generating tool head having at least one tool carrierfor generating tapered threads on a workpiece as a head housing and theworkpiece are given relative rotational and axial movements, improvedtool carrier actuating means comprising:an inner actuating bar movablysupported in and having an axis substantially coincident with the axisof the housing, the inner actuating bar having helical actuatingsurfaces formed thereon; a hollow cylindrical outer actuating bar havingan inner surface surrounding at least a portion of the inner actuatingbar and including helical actuating surfaces slidingly engaging thehelical actuating surfaces of the inner bar, the respective engaginghelical surfaces operative to cause rotating movement of the outer barin response to relative axial movement between the inner and outer bars;a stop member slidingly mounted in the housing, coupled to one of theinner and outer actuating bars, and positioned for abutting engagementwith the workpiece, operative to produce relative axial movement betweenthe inner and outer actuating bars in response to relative axialmovement between the housing and the workpiece; an annular actuatingtumbler surrounding at least a portion of the outer actuating bar andkeyed for rotation therewith about the housing axis; a sleevesurrounding at least a portion of the actuating tumbler; means forimparting linear axial movement to the sleeve in response to rotarymovement of the tumbler comprising at least a first helical slot formedin one of the sleeve and the tumbler and a key slidingly engaging thefirst helical slot and protruding from the other of the sleeve and thetumbler; and motion conversion means coupled between the sleeve and theat least one tool carrier operative to generate movement of the toolcarrier transverse to the housing axis by an amount proportional to theaxial movement of the sleeve.
 12. The improvement of claim 11 whereinthe means for imparting linear axial movement to the sleeve furthercomprises a plurality of helical slots, each having a different helixangle and each capable of slidingly receiving the key, whereby insertionof the key into a preselected one of the plurality of slots will producea preselected magnitude of axial movement by the sleeve upon a givenrotational movement of the tumbler.
 13. The improvement of claim 11wherein the motion conversion means further comprises;a drawbar coupledto the sleeve for linear axial motion therewith; a tool slide carryingthe at least one tool carrier and movably mounted to the housing forrelative motion transverse to the axis thereof; and a bell crankpivotally mounted to the housing and having a first portion coupled tothe drawbar and a second portion coupled to the tool slide, operative topivot in response to axial linear motion of the drawbar in a mannercausing movement of the tool slide transverse to the housing axis. 14.The improvement of claim 11 further comprising retract means forimparting additonal axial movement to the sleeve independently of therelative axial movement between the inner and outer bars produced by thestop member.
 15. The improvement of claim 11 further including aplurality of tool carriers, alternate carriers each having a first taperturning cutting element mounted thereon, the remainder of the pluralityof carriers each having a second taper turning cutting element and athread cutting element mounted thereon in axial alignment, each secondtaper turning element mounted axially forwardly of its associated threadcutting element.
 16. The improvement of claim 15 wherein the first andsecond taper turning cutting elements comprise a substantially circularindexable cutting insert and wherein the thread cutting elementscomprise multi-toothed thread chasing inserts.
 17. The improvement ofclaim 14 wherein the retract means further comprises:a flanged portionof the inner actuating bar; a push rod having one end coupled to theflanged portion; a tail section of the tool head slidingly mountedwithin the housing and positioned for abutting engagement with thesleeve for directly imparting axial motion thereto, the tail sectionfurther including a threaded extension coupled to the flanged portion; apilot portion of the tool head surrounding a portion of the tail sectionand containing at least one stop member for preventing axial movement ofthe tail section rewardly of the housing beyond a first predeterminedposition, a bore through a rear wall of the pilot portion through whichthe threaded extension of the tail section protrudes; a stop nutthreadingly engaging the extension and having a stop surface facing therear wall of the pilot portion to prevent axial movement of the tailsection forwardly of the housing beyond a second predetermined position;and means coupled to another end of the push rod for axiallyreciprocating the push rod over a range determined by the first andsecond predetermined positions.
 18. The improvement of claim 11 whereinthe at least one tool carrier includes means for adjustably mounting thetool carrier to the motion conversion means at a preselected radialdistance from the axis of the housing, whereby a continuous range ofworkpiece diameters may be threaded by the generating tool head.